Serrated throat

It looks like an extra from the muppet show, but this denizen of the deep is no cuddly toy. It lives in the frigid waters of the North Atlantic where the antifreeze in its blood keeps it alive as it rests in its underwater burrow. Behind the wolf fish’s fangs lie three rows of crushing teeth and even its throat is serrated.

A big wolf fish could weigh as much as 40 lbs and reach 5ft in length, but despite its fearsome looks, it’s only a danger to humans when caught and brought to the surface by their fishing equipment. The scary teeth aren’t even for use on other fish as its diet consists solely of shellfish and crustaceans.

Seeing double

Image source: Klaus StiefelThe South African mudskipper can see in air and water at the same time.

It’s just a humble South American mudskipper, but what makes this fish freaky is its bifocal vision. Because the four eyed fish feeds on both terrestrial insects and water born larvae, it has evolved to be able to see in both air and water. It has in fact two rather than four eyes, but each is divided in two by a strip of tissue. The upper and lower eyes filter light through a single lens whose thickness changes from top to bottom to cope with the different refractive qualities of air and water.

And just incase you think that isn’t weird enough, a right “handed” four eyed fish will only mate with a left “handed” female, and vice versa. Hows that for “un-natural selection”?

Sucked to death

Remember the film “Tremors”? Kevin Bacon and friends terrorised by giant carnivorous worms? The sea lamprey only grows to 90cm long, but in its own way, it’s just as scary.

Sucked to death – it must be a horrible way to go, but that’s exactly what the sea lamprey does to its hapless prey. It latches on with its sucker like mouth, then rows of sharp teeth scour through flesh and bone. An anticoagulant in the fish’s salival keeps the blood flowing, until it’s all gone and the prey dies. Then, the meal over, it’s time for the lamprey to lie in wait for a new host.

Killer cannibals

Image source: WikipediaNobody is safe from the lancet fish, not even its own family!

With its sail-like dorsal fin, gigantic spines and razor sharp teeth, the lancet fish looks like an extra from a dinosaur movie. And in reality, this ambush specialist is quite a piece of work. Its long thin body is difficult to spot in the water, and with its sail stored flat in a groove along its back, the lancet fish is almost invisible to its prey.

But when it pounces, the massive dorsal fin gives the fish powerful acceleration and once it sinks its sharp fangs into its prey, there’s no escape. A danger to each other as well as other fish, lancet fish are known to be cannibals.

Forehead Genitalia

It’s not a pretty sight, but the ghost fish is one of the oldest species of fish on the planet. Most closely related to sharks, in evolutionary terms, it diverged from that family over 400m million years ago. The fossil record shows they were once plentiful but these days, the ghost fish swims alone at depths between 200m and 2600m, making it a rare find.

The distinctive nose is actually used for detecting prey, but what makes the ghost fish truly creepy is that its sexual appendages are retractable and stored in its forehead.

Mirror image

Image source: Biology BiozineThe brownsnout spookfish can look up and down simultaneously.

It’s just a weird looking fish that swims at 1000m deep right? Wrong. The brownsnout spookfish is so rare that only one has ever been captured alive. And when one is caught, dead or not, it’s a cause of great excitement in the scientific community.

That’s because this fish is the only known creature on earth whose eyes use mirrors to capture light. The spook fish is able to look up and down at the same time. Upward facing apertures on the top of its head look for creatures silhouetted against the dim light of the distant surface while its downward facing eyes capture sparks and flashes from phosphorescing sea creatures beneath its vulnerable belly. This second pair of eyes reflects the specks of light onto the retina using mirrors made of crystal. Ingenious.